This didn't appear to work out of the box for me, so I'm hoping I just made a dumb mistake. My end result is that the following can be separate blogs under the same install of WP:
Here are the steps I've taken so far:
1) Install WP
2) Use wordpress.internaldomain.com as the main site
3) Enable subdomain blogs
4) Install domain mapping plugin
5) Create wordpress.internaldomain.com/food
6) Map http://www.anotherdomain.com to /food
After #6, it looks like http://www.anotherdomain.com IS the 'food' blog without the subdirectory. This implies that if I create 'entertainment' and map it to http://www.anotherdomain.com, there would be a collision.
Is there a way to achieve what I'm looking for?